Falling under the Environmental Protection Agency’s (EPA) hammer of “joint and several liability” in contaminated site cleanup cases is a costly proposition. Recently, the Supreme Court has thrown open the door to dividing these costs, and courts are now considering how to do it.

Joint and several liability is based on the legal concept that one entity can be solely responsible for the entire cost of cleanup regardless of whether other companies may have contributed to the problem. The EPA often threatens to seek full liability against companies that decline to settle. Contractors and site development professionals have potential liability if they work on or use sites that are contaminated. Site developers may be liable if they own or lease them.

In 2009, the Supreme Court endorsed “divisibility”—the notion that apportionment, not joint liability, is proper in some cases. This endorsement was widely viewed to open the possibility of settlements with the EPA based on fair shares for liability. But how can divisibility be proven?